Nuclear Reaction Studies using Stored Ion Beams at ESR with EXL

In this work, as part of the EXL project nuclear reactions are investigated in inverse kinematics experiments with stored ion-beams. These experiments were carried out at the heavy ion storage ring ESR at GSI with stored 58Ni (at 100 and 150 MeV/u) and 20Ne (at 50 MeV/u) beams. The 58Ni beam was impinged on an internal gas-jet target of helium, while for the 20Ne experiment the internal gas-jet target utilized was hydrogen. The recoil particles produced in different reaction channels were measured with a dedicated detector setup compatible with the Ultra High Vacuum (UHV) in the storage ring. This detector setup included double-sided silicon-strip detectors operating as active barriers between the UHV of the storage ring and an auxiliary vacuum of internal pockets of the experimental chamber. This permitted successful measurements of low energy recoils (hundreds of keV), since both target and detectors were windowless. Nuclear reaction channels like elastic scattering, excitation of isoscalar giant resonances and neutron pick-up were observed in these experiments. The angular distributions for elastic scattering were analyzed with optical potentials deduced from density-folding models. In particular, the elastic differential cross sections for 58Ni+ alpha were fitted by using the t-rho rho potential which is based on the optical limit approximation of the Glauber theory. The resulting RMS point matter-radii are 3.68(10) fm and 3.64(9) fm for the measurements at 100 and 150 MeV/u, respectively. These results are in very good agreement with the literature values. The excitation of isoscalar giant resonances has been studied for the first time in a stored-beam experiment. In the double-differential cross section measured for 58Ni+ alpha at 100 MeV/u, a well-defined peak in the energy range from 15 to 30 MeV was obtained. A fit with a Lorentz function for the Iso-Scalar Giant Monopole Resonance (ISGMR) component resulted in a centroid of 19.27(61) MeV and a width of 6.45(51) MeV. Moreover, a multipole decomposition analysis was performed to extract the ISGMR contribution. The extracted strength of the ISGMR exhausts 79^{+12}_{-11} \% of the Energy-Weighted Sum Rule (EWSR). The results are consistent with the analysis of other experiments performed in the past in normal kinematics as well as theoretical predictions. A neutron pick-up reaction was measured in the experiment with the stored 20Ne beam. In this experiment, the contribution of the transfer to the ground state and to low-lying states of 19Ne were not kinematically separable. In order to disentangle the different components, a multipole decomposition analysis was applied to the experimental data. Spectroscopic factors were deduced from the analysis of the differential cross section for this transfer reaction. These results are in very good agreement with the predictions from shell model calculations. The feasibility to perform different types of nuclear reactions with stored ion beams and an internal target by using in-ring detection is successfully demonstrated in this work. This is a paramount milestone toward further EXL experiments with radioactive beams at GSI and in future at FAIR

The Li-8(p, alpha)He-5 reaction at low energies, and Be-9 spectroscopy around the proton threshold

We present a direct measurement of the low-energy Li-8(p, alpha)He-5 cross section, using a radioactive Li-8 beam impinging on a thick target. With four beam energies, we cover the energy range between E-c.m. = 0.2 and 2.1 MeV. An R-matrix analysis of the data is performed and suggests the existence of two broad overlapping resonances (5/2(+) at E-c.m. = 1.69 MeV and 7/2(+) at E-c.m. = 1.76 MeV). At low energies our data are sensitive to the properties of a subthreshold state (E-x = 16.67 MeV) and of two resonances above threshold. These resonances were observed in previous experiments. The R-matrix fit confirms spin assignments, and provides partial widths. We propose a new Li-8(p, alpha)He-5 reaction rate and briefly discuss its influence in nuclear astrophysics. DOI: 10.1103/PhysRevC.86.064321Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP) [2003/10099-2, 2004/07379-6, 2008/09341-7]Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP)Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq)Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPq)Comissao de Aperfeicoamento do Ensino Superior (CAPES)Comissao de Aperfeicoamento do Ensino Superior (CAPES

Clonal chromosomal mosaicism and loss of chromosome Y in elderly men increase vulnerability for SARS-CoV-2

The pandemic caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2, COVID-19) had an estimated overall case fatality ratio of 1.38% (pre-vaccination), being 53% higher in males and increasing exponentially with age. Among 9578 individuals diagnosed with COVID-19 in the SCOURGE study, we found 133 cases (1.42%) with detectable clonal mosaicism for chromosome alterations (mCA) and 226 males (5.08%) with acquired loss of chromosome Y (LOY). Individuals with clonal mosaic events (mCA and/or LOY) showed a 54% increase in the risk of COVID-19 lethality. LOY is associated with transcriptomic biomarkers of immune dysfunction, pro-coagulation activity and cardiovascular risk. Interferon-induced genes involved in the initial immune response to SARS-CoV-2 are also down-regulated in LOY. Thus, mCA and LOY underlie at least part of the sex-biased severity and mortality of COVID-19 in aging patients. Given its potential therapeutic and prognostic relevance, evaluation of clonal mosaicism should be implemented as biomarker of COVID-19 severity in elderly people. Among 9578 individuals diagnosed with COVID-19 in the SCOURGE study, individuals with clonal mosaic events (clonal mosaicism for chromosome alterations and/or loss of chromosome Y) showed an increased risk of COVID-19 lethality

Nuclear Reaction Studies using Stored Ion Beams at ESR with EXL

In this work, as part of the EXL project nuclear reactions are investigated in inverse kinematics experiments with stored ion-beams. These experiments were carried out at the heavy ion storage ring ESR at GSI with stored 58Ni (at 100 and 150 MeV/u) and 20Ne (at 50 MeV/u) beams. The 58Ni beam was impinged on an internal gas-jet target of helium, while for the 20Ne experiment the internal gas-jet target utilized was hydrogen. The recoil particles produced in different reaction channels were measured with a dedicated detector setup compatible with the Ultra High Vacuum (UHV) in the storage ring. This detector setup included double-sided silicon-strip detectors operating as active barriers between the UHV of the storage ring and an auxiliary vacuum of internal pockets of the experimental chamber. This permitted successful measurements of low energy recoils (hundreds of keV), since both target and detectors were windowless. Nuclear reaction channels like elastic scattering, excitation of isoscalar giant resonances and neutron pick-up were observed in these experiments. The angular distributions for elastic scattering were analyzed with optical potentials deduced from density-folding models. In particular, the elastic differential cross sections for 58Ni+ alpha were fitted by using the t-rho rho potential which is based on the optical limit approximation of the Glauber theory. The resulting RMS point matter-radii are 3.68(10) fm and 3.64(9) fm for the measurements at 100 and 150 MeV/u, respectively. These results are in very good agreement with the literature values. The excitation of isoscalar giant resonances has been studied for the first time in a stored-beam experiment. In the double-differential cross section measured for 58Ni+ alpha at 100 MeV/u, a well-defined peak in the energy range from 15 to 30 MeV was obtained. A fit with a Lorentz function for the Iso-Scalar Giant Monopole Resonance (ISGMR) component resulted in a centroid of 19.27(61) MeV and a width of 6.45(51) MeV. Moreover, a multipole decomposition analysis was performed to extract the ISGMR contribution. The extracted strength of the ISGMR exhausts 79^{+12}_{-11} \% of the Energy-Weighted Sum Rule (EWSR). The results are consistent with the analysis of other experiments performed in the past in normal kinematics as well as theoretical predictions. A neutron pick-up reaction was measured in the experiment with the stored 20Ne beam. In this experiment, the contribution of the transfer to the ground state and to low-lying states of 19Ne were not kinematically separable. In order to disentangle the different components, a multipole decomposition analysis was applied to the experimental data. Spectroscopic factors were deduced from the analysis of the differential cross section for this transfer reaction. These results are in very good agreement with the predictions from shell model calculations. The feasibility to perform different types of nuclear reactions with stored ion beams and an internal target by using in-ring detection is successfully demonstrated in this work. This is a paramount milestone toward further EXL experiments with radioactive beams at GSI and in future at FAIR

Study of elastic scattering of the isotopes 7Be, 9Be and 10Be on 12C target

Nesse trabalho medimos e analisamos distribuições angulares do espalhamento elástico para os isótopos 7Be, 9Be e 10Be em alvo de 12C. A distribuição do 7Be foi medida a uma energia de 18.8 MeV, em dois laboratórios, com o sistema TWINSOL, na Universidade de Notre dame, e com o sistema RIBRAS, na Universidade de São Paulo, onde foi completada a distribuição angular. As distribuições para o 9Be e 10Be foram medidas completamente no sistema RIBRAS, em energias de 26.0 e 23.2 MeV, respectivamente. Cada uma dessas distribuições angulares foi analisada considerando no modelo ótico e também o formalismo dos canais acoplados. Testamos múltiplos potenciais óticos em cada distribui9ção, com a finalidade de descrever a seção de choque elástica de cada sistema. Para os sistemas que envolvem núcleos fracamente ligados (7Be, 9Be e 8B) foram feitos cálculos com acoplamento do contínuo (CDCC), enquanto que para o núcleo 10Be, que é fortemente ligado, acoplamos os dois primeiros estados ligados. Também, a partir da análise de cada uma das distribuições elásticas, foi possível obter a seção total de reação, que foi comparada sistematicamente com outros núcleos leves espalhados em carbono. Dessa análise foi possível concluir que o canal do break up Coulombiano, nesses sistemas leves, não é fortemente influente na seção de choque total de reação, o que implica que a interação entre alvo e projétil é dominada pelo potencial nuclear.In the present work, we measured elastic scattering angular distributions for teh isotopes 7Be, 9Be and 10Be on 12C target. The angular distribution of 7Be at 18.8 MeV, was measured in two laboratories, with the TWINSOL system, in Notre Dame University, and the RIBRAS system, in São Paulo University, where the angular distribution was completed. The angular distribution for 9Be and 10Be isotopes measured completely in the RIBRAS system at 26.0 and 23.2 MeV, respectively. All angular distribution were analized considering optical model and coupled channel formalism. We tested multiple optical potentials on each distribution to describe the elastic cross section for these systems. For the weakly bound projectiles (7Be, 9Be and 8B)calculations with continous coupling (CDCC) were performed, while for the 10Be nucleus, which is tghtly bound nucleus, we coupled the first two bound states. We also performed a systematic analysis of the total reaction cross section obtained from elastic scattering distribution of several light particles on 12C. From this analysis, we concluded that the Coulomb break up channel, in these light systems, does not have a strong influence on the total reaction cross section, what implies that the projetile-target interaction is dominated by the nuclear potential

Elastic scattering and total reaction cross sections for the (8)B, (7)Be, and (6)Li+(12)C systems

Angular distributions for the elastic scattering of (8)B, (7)Be, and (6)Li on a (12)C target have been measured at E(lab) = 25.8, 18.8, and 12.3 MeV, respectively. The analyses of these angular distributions have been performed in terms of the optical model using Woods-Saxon and double-folding type potentials. The effect of breakup in the elastic scattering of (8)B + (12)C is investigated by performing coupled-channels calculations with the continuum discretized coupled-channel method and cluster-model folding potentials. Total reaction cross sections were deduced from the elastic-scattering analysis and compared with published data on elastic scattering of other weakly and tightly bound projectiles on (12)C, as a function of energy. With the exception of (4)He and (16)O, the data can be described using a universal function for the reduced cross sections.Conselho Nacional de Pesquisa e Desenvolvimento (CNPq)Conselho Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES)Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP)National Science Foundation NSF[PHY-0652591]National Science Foundation NSF[PHY-0969456]CONACYT (Mexico

Elastic scattering measurements for [sup 7]Be+[sup 27]Al system at RIBRAS facility

Elastic scattering angular distribution measurements of 7Be_27Al system were performed at the laboratory energy of 15.6MeV. The 7Be secondary beam was produced by the proton transfer reaction 3He (6Li, 7Be) and impinged on 27Al and 197Au targets, using the Radioactive Ion Beam (RIB) facility, RIBRAS. The elastic angular distribution was obtained within the angular range of 15° - 80° at the center of mass frame. Optical model calculations have been performed using the Woods- Saxon form factors and the São Paulo potential to fit the experimental data. The total reaction cross section was derived.CNPqFAPER

Experimental study of (6)He + (9)Be elastic scattering at low energies

New data for the (6)He + (9)Be reaction at E(1ab) = 16.2 and 21.3 MeV have been taken and analyzed. The effect of the collective couplings to the excited states of the target has been studied by means of coupled-channels calculations, using a double-folding potential for the bare interaction between the colliding nuclei, supplemented with a phenomenological imaginary part of Woods-Saxon type. In addition, three- and four-body continuum-discretized coupled-channels calculations have been performed to investigate the effect of the projectile breakup on the elastic scattering. Both effects, the coupling to target and projectile excited states, are found to affect significantly the elastic scattering. The trivial local polarization potential extracted from the continuum-discretized coupled-channels calculations indicates that continuum couplings produce a repulsive real part and a long-range imaginary part in the projectile-target interaction.Junta de AndaluciaFAPESPBanco SantanderSpanish Ministerio de Ciencia e Innovacion[FPA2009-07653]Spanish Ministerio de Ciencia e Innovacion[PCI2006-A7-0654]Spanish Consolider-Ingenio[CSD2007-00042

(7,9,10)Be elastic scattering and total reaction cross sections on a (12)C target

Elastic scattering angular distributions for (7)Be, (9)Be, and (10)Be isotopes on (12)C target were measured at laboratory energies of 18.8, 26.0, and 23.2 MeV, respectively. The analysis was performed in terms of optical model potentials using Woods-Saxon and double-folding form factors. Also, continuum discretized coupled-channels calculations were performed for (7)Be and (9)Be + (12)C systems to infer the role of breakup in the elastic scattering. For the (10)Be + (12)C system, bound states coupled-channels calculations were considered. Moreover, total reaction cross sections were deduced from the elastic scattering analysis and compared with published data on other weakly and tightly bound projectiles elastically scattered on the (12)C target, as a function of energy.Conselho Nacional de Pesquisa e Desenvolvimento (CNPq)Fundacao de Amparo a Pesquisa do Estado de Sao Paulo (FAPESP